Field of the Invention
The present invention relates to a polishing apparatus and method for polishing a surface of a substrate such as a semiconductor wafer by relative movement between the surface of the substrate to be polished and a polishing pad on a polishing table while the substrate is pressed against the polishing pad, and more particularly to a polishing apparatus and method which can control a temperature of the surface (polishing surface) of the polishing pad by blowing a gas on the polishing pad.
Description of the Related Art
In recent years, high integration and high density in semiconductor device demands smaller and smaller wiring patterns or interconnections and also more and more interconnection layers. Multilayer interconnections in smaller circuits result in greater steps which reflect surface irregularities on lower interconnection layers. An increase in the number of interconnection layers makes film coating performance (step coverage) poor over stepped configurations of thin films. Therefore, better multilayer interconnections need to have the improved step coverage and proper surface planarization. Further, since the depth of focus of a photolithographic optical system is smaller with miniaturization of a photolithographic process, a surface of the semiconductor device needs to be planarized such that irregular steps on the surface of the semiconductor device will fall within the depth of focus.
Thus, in a manufacturing process of a semiconductor device, it increasingly becomes important to planarize a surface of the semiconductor device. One of the most important planarizing technologies is chemical mechanical polishing (CMP). Thus, there has been employed a chemical mechanical polishing apparatus for planarizing a surface of a semiconductor wafer. In the chemical mechanical polishing apparatus, while a polishing liquid containing abrasive particles such as silica (SiO2) or ceria (CeO2) therein is supplied onto a polishing pad, a substrate such as a semiconductor wafer is brought into sliding contact with the polishing pad, so that the substrate is polished.
A polishing apparatus for performing the above CMP process includes a polishing table having a polishing pad, and a substrate holding device, which is referred to as a top ring or a polishing head, for holding a substrate such as a semiconductor wafer. When the semiconductor wafer (substrate) is polished by using such a polishing apparatus, the semiconductor wafer is held and pressed against the surface (polishing surface) of the polishing pad under a predetermined pressure by the substrate holding device while a polishing liquid (slurry) is supplied from a polishing liquid supply nozzle onto the polishing pad. At this time, the polishing table and the substrate holding device are rotated to bring the semiconductor wafer into sliding contact with the polishing surface, so that the surface of the semiconductor wafer is polished to a flat mirror finish.